Conventionally, there is known surface light source device 100 in which a light guide plate is not used, as illustrated in FIG. 56. In surface light source device 100 illustrated in FIG. 56, a plurality of light-emitting elements 103 are attached to opposing side walls 102 and 102 of hollow casing 101 so as to face each other. Light from light-emitting element 103 is radiated to internal space 105 of casing 101 through rod-shaped cylindrical lens 104. The light radiated through cylindrical lens 104 is diffused and reflected toward the roof side (the side opposite to bottom 106 of casing 101) by reflection member 107 disposed on bottom 106 of casing 101. The light reflected by reflection member 107 is emitted in a planar fashion from opening (display window) 110 of the roof toward the outside of casing 101 through light diffusion plate 108 (see PTL 1).